<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Map</title>
</head>
<body>

<script>
    let map = new Map();
    //       key   value
    map.set("CH","中华人民共和国");
    map.set("USA","美利坚共和国");
    map.set("JP","小日本");
    map.set("JP","日本");
    console.log(map.size);
    for(let keys of map.keys()){
        console.log("map:key "+keys);
        console.log("map:key "+map.get(keys));//获取value值
    }
    for(let value of map.values()){
        console.log("map:value "+value);
    }
</script>
</body>
</html>